U.S. patent number 4,377,975 [Application Number 06/264,260] was granted by the patent office on 1983-03-29 for axle mounted alternator for railroad cars.
Invention is credited to Dudley C. Peters, John P. Scott.
United States Patent |
4,377,975 |
Scott , et al. |
March 29, 1983 |
Axle mounted alternator for railroad cars
Abstract
An alternator, including a rotor unit, a housing and stator unit
rotatably mounted to and supported by the rotor unit, includes
apparatus for mounting the alternator to the end of a rotating axle
of a railroad vehicle.
Inventors: |
Scott; John P. (San Anselmo,
CA), Peters; Dudley C. (Acampo, CA) |
Family
ID: |
23005249 |
Appl.
No.: |
06/264,260 |
Filed: |
May 18, 1981 |
Current U.S.
Class: |
105/96.1;
105/133; 290/3 |
Current CPC
Class: |
H02K
7/1846 (20130101); B61H 9/06 (20130101); B61D
43/00 (20130101); B60K 25/08 (20130101); B61C
9/48 (20130101); Y02T 30/36 (20130101); Y02T
30/00 (20130101) |
Current International
Class: |
B60K
25/00 (20060101); B60K 25/08 (20060101); B61C
9/00 (20060101); B61D 43/00 (20060101); B61C
9/48 (20060101); B61H 9/06 (20060101); B61H
9/00 (20060101); H02K 7/18 (20060101); B61C
009/48 (); B61C 017/00 (); B61D 043/00 () |
Field of
Search: |
;105/96,96.1,133
;267/57.1A,57.1R,63A,136,141,152,153 ;290/1C,1R,3 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Reeves; Robert B.
Assistant Examiner: Beltran; Howard
Attorney, Agent or Firm: Townsend and Townsend
Claims
What is claimed is:
1. An alternator for mounting to an end of a rotatable axle of a
vehicle, said alternator comprising:
a housing;
a stator mounted to and within said housing;
a rotor contained by said housing, the housing being rotatably
mounted to and supported by the rotor, said rotor being operably
positioned with respect to said stator;
means for removably securing the rotor to the axle end and for
supporting the rotor in concentric relation with the axle for
rotation therewith, the rotor rotatably supporting the stator and
housing; and
means mounted to the vehicle and operably coupled to the housing
for inhibiting rotation of the housing and the stator when the
rotator is rotated by the axle, the inhibiting means including a
recess formed on an outer surface of the housing and arm structure
extending from the vehicle and engaging said recess.
2. The alternator of claim 1, wherein the securing means includes
an elongate extension member affixed to the axle end and coaxial
with the axle, the rotor being configured to receive and be
removably mounted on the extension member and supported
thereby.
3. The alternator of claim 1, wherein the recess of the inhibiting
means is in the form of an aperture formed on and adjacent the
housing, the arm structure being dimensioned to engage the aperture
to inhibit rotation of the housing.
4. Electrical generating equipment for mounting to the end of a
rotatable axle of a vehicle, comprising:
a rotor unit;
means for attaching the rotor unit to the axle and in coaxial
relation thereto, the attaching means including an end cap element
removably affixed to the axle end, the end cap having a threaded
aperture formed therein coaxial with the axle, a threaded stress
pin positioned in said aperture to operably engage the axle end,
and an extension element removably connected to the end cap and
structured to extend coaxially from the axle and to receive and
support the rotor unit in fixed relation to the axle, the extension
element including means for holding the stress pin immovable;
a stator unit rotatably mounted to the rotor unit;
a housing secured to the stator unit and enclosing the stator and
rotor units, the housing having an outer surface upon which is
formed an aperture; and
structure coupled to the vehicle and including an elongate bar
element extending from the vehicle and towards the electrical
generating equipment, the bar element having a portion for engaging
the aperture formed on the housing outer surface.
5. An alternator mountable to an end of an axle of a railroad
vehicle, the axle having a recess formed in the axle end concentric
with the axle and a bearing assembly for rotatably supporting the
railroad vehicle on the axle, the alternator comprising:
a rotor unit;
a housing containing the rotor unit;
a stator unit contained within and secured to the housing, the
stator and housing being mounted to and rotatably supported by the
rotor unit;
an end cap having a threaded aperture formed therethrough;
first means for securing the end cap to the axle end for rotation
therewith, the threaded aperture being concentric with the axle
recess, the securing means including bolt means having a threaded
portion extending through the threaded aperture and terminating in
an end portion formed and configured to matably engage the
recess;
second means for securing the rotor unit to the end cap for
rotation therewith, the second means including an annular element
adapted to extend coaxially from the axle and to receive and
support the rotor unit; and
structure, including an elongate, rigid member, mounted to the
railroad vehicle, the elongate member engaging the housing to
inhibit rotational movement thereof when the rotor is rotated.
6. The alternator of claim 5, and second securing means having a
second recess formed therein coaxial with and confronting the
threaded aperture of the end cap, the bolt means having head
structure formed at an end thereof opposite the end portion, the
second recess being configured to receive and hold the head
structure against relative rotational movement therebetween.
7. The alternator of claim 5, wherein the aperture is an eye
structure.
8. The alternator of claim 5, wherein the recess is conically
shaped and the end portion of the bolt means is structured to
conformably mate with the conically shaped recess.
9. The alternator of claim 8 wherein the annular element includes
means for holding the bolt means in immovable engagement with the
conically shaped recess.
10. Apparatus for mounting an alternator to an end of a rotatable
axle of a vehicle, the alternator being of the type having a rotor
and a stator rotatably mounted to and supported by the rotor, the
axle having a concentrically located recess formed in the end
thereof and a bearing assembly for rotatably holding the axle, the
apparatus comprising:
an end cap adapted to be secured to the axle end for rotation
therewith, the end cap being adapted to hold the bearing assembly
spaced from the axle end and having formed therethrough a threaded
aperture substantially concentric with the axle;
bolt means having a pair of opposed ends and a threaded portion
proximate one of the opposed ends adapted to be engageable with the
threaded aperture, the one of the opposed ends being formed and
configured for mating engagement with the recess in the axle;
means for removably securing the rotor to the end cap for rotation
therewith; and
means for intercoupling the alternator and a portion of the vehicle
for inhibiting rotational movement of the alternator when the rotor
is rotated by rotation of the axle.
Description
This invention relates generally to apparatus for mounting
machinery to the end of a rotatable axle of a vehicle and, more
particularly, to mounting an alternator to the end of a rotating
axle of railroad cars.
BACKGROUND OF THE INVENTION
In the railroad industry, electrical energy is supplied for
individual railroad cars, such as a caboose, by employing the
rotational energy derived from a rotating shaft such as a rotating
axle. The most common method of transmitting this rotational energy
is to use "V"-Belts and pulleys in various ways. The transmitted
rotational energy is then used to produce the necessary mechanical
power that drives a variety of machinery such as electrical
generating equipment (i.e., generators or alternators).
However, this system of transmitting the rotational energy
transmission is not without problems. For example, the "V"-Belts
attached to the rotating axle are often required to operate in an
environment that is exposed to a number of hazards, including the
elements. Thus, while the railroad vehicle is traveling
cross-country, the rotating axle is often exposed to dirt, grit,
rocks, sticks, and the like, thrown up the moving vehicle. In
addition, railroad vehicles often traverse substantial distances in
short amounts of time and, accordingly, are subjected to, and in
turn subject these "V"-belts to, large temperature variations. All
this greatly increases the wear imposed upon the "V"-belts energy
transmission system. In turn, the rotational energy transmission
system often requires part replacement and/or adjustments
necessitated by such wear.
When a belt breaks or becomes unusable due to wear, replacement is
a time consuming and expensive operation; an operation that must be
performed in a railroad yard equipped to separate the axle, to
which the system (i.e., the "V"-belts) is coupled, from the
railroad car in order to replace damaged or broken belt or
belts.
In addition, recent increases in electrical requirements of many
railroad cars have been limited by the torque requirements of high
capacity generators or alternators. The torque transmitting
capabilities of "V"-belt systems cannot drive such high capacity
equipment efficiently. One attempted solution is to use two or more
"V"-belts where, before, only one was used. However, that this
solution is negligible because one belt usually wears or stretches
more than the other or others, the end result being that only one
belt actually performs the rotational energy transmitting
function.
What the railroad industry presently does is to use low torque
generators or alternators that are designed to produce the required
electrical energy by operating at high revolutions-per-minute (RPM)
in order to not exceed the torque transmitting capabilities of
"V"-belted transmission systems. This requires, however, that one
particular "V"-belt transmission system be used when the vehicle is
operated at high rates of speed, such as on a cross-country trip,
and another particular "V"-belt transmission system in order to
continue to operate the generator or alternator at a sufficiently
high RPM, while the vehicle travels at a low rate of speed, such as
while being used in a freight yard. The change from one system to
another usually involves changing and adding "V"-belts and pulleys,
again a time-consuming and expensive chore.
It can be seen, therefore, that there exists a need for electrical
generating equipment of sufficiently high capacity that can be
employed by a vehicle having a rotating axle for driving the
electrical equipment. Preferably, the electrical equipment will be
coupled to the rotating axle in a manner that allows sufficient
torque to be developed to operate the equipment at all reasonable
vehicle speeds, yet allow the generator to be easily replaced. In
addition, the method of coupling the generator to the rotating axle
should not require extensive modification of the axle or its
associated parts.
SUMMARY OF THE INVENTION
The present invention provides an alternator capable of being
removably mounted directly to the end of a rotating axle of a
railroad vehicle. The invention comprises an alternator, including
a rotor unit rotatably supporting a stator unit, and a housing that
is affixed to enclose the stator unit and contains both the rotor
and the stator units, and apparatus for mounting the alternator to
an end of an axle for rotating of the rotor therewith.
In the preferred embodiment, the rotor is structured to be
slideably received by and removably attached to an extension
element that is mountable to the end of the rotating axle by an end
plate that attaches directly to the axle, holding the extension
element in concentric relation with the axle. A threaded aperture
is formed in the end plate at a location that is concentric with
the axle when the end plate is attached to the end thereof. The
aperature receives a stress pin that engages the axle in a manner
that assists in relieving stresses that would be otherwise be
imparted to the axle and the bearing assembly that supports the
axle, allowing the alternator to be supported by the axle. However,
since the entire alternator structure is supported entirely by the
axle, something must keep the stator from rotating while the rotor
is allowed to rotate with the axle in order to generate electrical
power. Accondingly, an elongate member is mounted to a non-rotating
portion of the vehicle and structured to extend to and engage a
recess formed in the outer surface of the housing of the
alternator. Rotation of the axle directly causes the extension
element, and the alternator's rotor attached thereto, to also
rotate. The stator and housing, rotatably supported by the rotor,
are also induced toward rotational movement, but inhibited
therefrom by the elongated member that engages the housing.
A number of advantages are obtained by the present invention.
First, since the alternator and the apparatus used to drive the
rotor unit of the alternator, are situated at the end of the
rotating axle which therefore, makes them easily accessible for
removal and replacement should the need arise. Further, the rotor
unit of the alternator is directly coupled to the rotating axle,
thereby allowing a high-torque, high capacity alternator (or
generator) unit to be used. In addition, as will be fully explained
in the detailed description below, the mounting of the alternator
to a rotating axle requires a minimal of modification to the
presently existing axle and its associated assembly. Further still,
the weight of the alternator is carried solely by the extension
member that is coupled to the axle end by the end cap. By providing
a stress pin that is substantially coaxial with and engages the
axle, the stresses imparted by the alternator's weight are
transmitted to the axis of the axle without harm to the axle or its
associated components.
These and other features and advantages of the present invention
will be more readily apparent from the following detailed
description of the preferred embodiment, wherein reference is to be
made to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a exploded, perspective view of an alternator constructed
and mounted in accordance with the present invention, to the end of
a rotating axle of a railroad vehicle;
FIG. 2 is a side elevation, partly in section, of the end of a
rotating axle, illustrating the manner in which the attachment
apparatus is secured to the end of the axle;
FIG. 3 is a sectional view of the alternator of FIG. 1; and
FIG. 4 is a sectional view, taken along the lines 4--4 in FIG. 1,
of the eye member formed on the housing of the alternator,
illustrating engagement between the eye member and a torsion bar
assembly.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring initially to FIG. 1, there is depicted, in exploded view,
an alternator A mounted to the end of a rotating axle in accordance
with the preferred embodiment of the present invention wherein the
vehicle carried by the axle comprises a railroad car, such as a
caboose. As illustrated, the alternator A is adapted to couple to
an axle extension member B which, in turn, is removably attached by
a bearing cap C to an axle hub 12 of axle 13.
Typically, the railroad car (not shown) rests upon a truck 10
(illustrated in phantom) that, in turn, is rotatably mounted on an
axle hub 12 by an axle-encircling roller bearing assembly 14. A
mounting flange or buffer 16, interposed between the truck 10 and
bearing assembly 14, allows relative movement between the truck 10
and the axle hub 12/bearing assembly combination during travel of
the vehicle over less than smooth track. The terminal portion of
the axle hub 12 is provided a transverse planar end face 20 and,
formed in the center of the end face 20 and in substantial
concentric alignment with the axle, is a conically shaped
countersink recess 22. This countersink recess is found in the end
face 20 of most axle hubs 12 used in the railroad industry; it is
formed during manufacture of the axle hub 12 and used by lathe
apparatus as an alignment spot when truing the outer surface 24 of
the axle hub 12 to the axis of the axle.
The bearing assembly 16 is friction-fitted onto the axle hub 12,
and held in place by the bearing cap C that is attached by threaded
bolts (not shown in FIG. 1) which extend through apertures 28
formed in the bearing cap C to engage threaded apertures 30 formed
in the planar face 20 of the axle hub 12. The bearing cap C is
modified from that typically used in order to incorporate the
present invention. One such modification is a centrally located
threaded aperture 32 formed at a position that ensures substantial
concentric alignment with the recess 22 and the longitudinal axis
of the axle hub 12 when the bearing cap C.
The threaded aperture 32 receives a stress pin D that is formed to
have a frusto-conical terminal portion configured to conformably
engage and operably mate with the conical recess 22 of the axle hub
of 12 (FIG. 2).
A raised annular ring 36 is formed on one side 38 of the bearing
cap C, wherein there is also formed a number of spaced, threaded
bores 40.
The axle extension member B is preferably a unitary structure that
includes a disk-like flange 44 from which perpendicularly extends a
cylindrical shaft 46. Threaded apertures 48 are formed at the end
of the shaft 46; and, formed in the flange 44 at spaced locations
adjacent its periphery, are a number of bores 50. Each bore 50 is
located so that it will be coaxial with a corresponding one of the
threaded bores 40 formed in the annular flange 36 of the bearing
cap C. The apertures 50 receive and pass therethrough bolts 50a
(FIG. 2) which are adapted to be threaded in the apertures 30 of
the bearing cap C to thereby attach the axle extension member B to
the bearing cap C.
The shaft 46 of the axle extension member B is adapted to receive
and support thereon the alternator A by passing through a centrally
located bore 54 formed in the alternator. When the alternator A is
placed upon the axle extension member B, an end cap 56 is affixed
to the end of the shaft 46 by cap screws 58 which pass through cap
screw holes 60 formed in the end cap 56 to engage the threaded
apertures 48 formed in the shaft 46. Also formed in the end cap 56
are outer apertures 62 through which pass rotor screws 64 to
thereby secure the axle extension member B to a rotating part (not
shown in FIG. 1) of the alternator A in a manner that will be
described more fully below.
Attached to a non-rotating part of the railroad vehicle, the truck
10, is a torsion bar assembly E. Torsion bar assembly E is a
unitary structure that includes a rigid, elongated arm element 68
that extends from a mounting plate 70. Formed in the mounting plate
70 is an aperture 72 through which passes a threaded torsion bolt
74 that is used to fixedly attach the torsion bar assembly to the
truck 10. When so attached, the arm element 68 extends in a
direction parallel to the longitudinal axis of the hub 12 and away
from the truck 10. The arm element 68 is provided with a
longitudinal dimension sufficient to allow, when the alternator A
is mounted to the axle hub 12, the end portion 68a of the arm 68 to
engage and even protrude through an eye member 76 formed on the
outer surface of the alternator A.
Turning now to FIG. 2, the axle extension member B, bearing cap C,
and their attachment to one another, and to the axle hub 12 is
illustrated in greater detail. As shown, the axle hub 12 rotatably
supports the railroad vehicle (not shown) by a roller bearing
assembly 16 via the truck 10 (illustrated in phantom in FIG. 1).
The roller bearing assembly 16, manufactured by Brenco Inc. of
Petersburg, Virginia, or Timken Company, of Canton, Ohio, typically
includes a journal box which encloses a number of roller bearings
82 that are rotatably held between a pair of opposing, concentric
bearing races 84 and 86. Such roller bearing assemblies are usually
prepacked with a lubricant (i.e. grease) during manufacture. The
lubricant held within, and prevented from leaking from, the bearing
assembly 16 by a grease seal 88 and annular wear ring 90 of
well-known design.
The roller bearing assembly 16 is force-fitted onto the axle hub 12
in a known manner and under very tight tolerances. In order to
prevent the roller bearing assembly from sliding off the axle hub
12 during extended use, the wear ring 90 is extended outward at 92
to engage and bear against a cylindrical shoulder 94 formed in the
bearing cap C. Thus, when the bearing cap C is mounted to the end
of the axle hub 12, via hub bolts 29, the extension 92 of the wear
ring 90 conformably mates with the shoulder 94; the roller bearing
assembly 16 is thereby prohibited from moving along the axle hub 12
in the direction of the bearing cap C.
Heretofore, under typical use, only a bearing cap is attached to
the end of the axle hub 12. Accordingly, the stresses placed on the
wear ring 90 at the extension 92 by the bearing cap C are minimal;
and whatever stresses that are present are provided for by
manufacturing the wear ring from case hardened steel. In addition,
because there is a minimal force imposed upon the extension 92 of
the wear ring 90 by the bearing cap C, no substantial attempt is
made to hold the wear ring C immovable relative to the wear ring;
that is, a certain amount of transverse movement of the bearing cap
C is allowed by the relatively large tolerances between the
diameters of apertures 28 and size of hub lots 92. However, when
the bearing cap is modified, as is the bearing cap C, in order to
carry the additional weight of the axle extension member B and
alternator A, the stresses placed on the wear ring 90 can become
extreme. Further, this addition weight creats greater lateral
forces and movement of the bearing cap C. The result can be
increased wear or breakage of the wear ring 90, necessitating its
early replacement.
In order to relieve the wear ring 90 from these additional
stresses, the following is provided: The threaded aperture 32 is
formed in the bearing cap C--at a location that is substantially
coaxial with the countersink recess 22 formed in the axle hub 12
when the bearing cap C is attached. With the bearing cap C attached
to the axle hub 12, the stress pin D is threaded into and through
the threaded aperture 32 until a frusto-conically configured
terminal portion 96 of the stress pin D engages and conformably
mates with the countersink recess 22, as illustrated. When
tightened, the stress pin D functions to hold the bearing cap
fixed, prohibiting lateral movement of the bearing cap C relative
to the wear ring 90, and to carry a major portion of the stresses
placed upon the bearing cap C by the weight of the alternator A,
thereby relieving the extension 92 from any additional wear or
force.
The stress pin D, when in place, as shown in FIG. 2, is provided
with a hexagonally shaped head 100 portion extends from the bearing
cap C. In order to allow the axle extension member B to be attached
to the bearing cap C there is a hexagonal recess 102 formed in the
back-side of the axle extension member B that is configured to
receive the extending stress pin portion 100. This recess 102
performs a two-fold function: It allows the axle extension member B
to be used to tighten or remove the stress pin D; and, when the
axle extension member B is fastened to the bearing cap C via the
bearing cap bolts 50a, it holds the stress pin D in place,
prohibiting it from backing away from the recess 22 of the axle hub
12 and minimizing its usefulness.
It should be evident that Care should be taken to form the axle
extension member B and the bearing cap C so that when attached to
the axle hub 12, all are configured and concentrically oriented to
minimize any unbalance during axle rotation.
Referring now to FIG. 3, the alternator A is shown in greater
detail as including a rotor 110 which is constructed to form the
opening 54 of the alternator A that receives the shaft 56 of the
axle extension member B. Rotatably mounted on the rotor 110 is a
housing 111 formed from several parts: an outboard bell housing
112, an outboard stator housing 114, an inboard stator housing 116;
and, an inboard bell housing 118. The individual parts 112, 114,
116 and 118 of the housing 111 are connected together by
appropriate fastening means such as the nut and bolt combinations
120 illustrated in FIG. 3. Interposed between the rotor 110 and the
housing assembly are self-aligning spherical roller bearings 120a
and 120b, each comprising inner and outer annular bearing races 122
and 124, respectively, held relatively spaced from one another in
concentric orientation by a number of cylindrical bearings 128.
Affixed to the inboard and outboard stator housings 114, 116, and
in surrounding relation to the rotor 54, is a stator 130 of
conventional design, including a stator winding 132 that encircles
a number of stator lamination plates 134, and a field coil 136.
The roller bearing 120a and 120b are each prepacked with a
lubricant that is maintained within the bearing area by outer and
inner seals 140 and 142, respectively, of conventional design.
The alternator A is mounted to the shaft 46 of the axle extension
member B by inserting the shaft into the opening 54 of the
alternator. The end cap 56 is then positioned in confronting
relation to the end of the shaft 46 and the apertures 60 aligned
with corresponding threaded apertures 48 formed in the shaft 46
(FIGS. 1 and 2). Cap screws 58 secure the end cap 56 to the shaft
46.
Also formed in the end cap 56 are apertures 62, positioned to be
aligned with threaded bores 154 formed in the rotor 110 (FIG. 3).
Rotor bolts 64 are provided to secure the end cap 56 to the rotor
110 to the axle extension member B.
When the entire structure is secured to the axle hub 12, as
described above, and the railroad vehicle moved, the axle, and axle
hub 12, will begin to rotate. Thereby, rotational energy is
transmitted via the bearing cap C, axle extension member B to the
rotor 110. As the rotor 110 revolves, the housing and stator 130,
which are rotatably supported by the rotor 110 through the roller
bearings 120a and 120b, will also tend to rotate. Rotation of this
latter assembly, however, is inhibited by the arm element 68 of the
torsion bar assembly E whose end portion 68a engages the eye member
76 formed on the housing.
Illustrated in FIG. 4 is a sectional view of the eye member 76,
taken along the line 4--4 of FIG. 1. FIG. 4 also illustrates
engagement of the eye member 76 by the end portion 68a of arm
element 68. Preferably, when the alternator A is assemble and
mounted to the axle hub 12, and with the torsion bar assembly E
mounted to a non-rotating part of the vehicle, the arm member 68
will be sufficiently dimensioned to allow the end portion 68a to
pass through the opening 77 formed by the eye member 76--as FIG. 4
illustrates.
Note that the confronting inner surfaces 78 of the eye member 76
are rounded. When the vehicle moves, the non-rotating portion of
the vehicle to which the torsion bar assembly E is attached is
often subjected to forces that result in movement not experienced
by the axle, the axle hub 12, and therefore, the alternator A
attached thereto. Thus, the rounded inner surfaces 78 allow the end
portion 68a of the torsion bar assembly E to "float" and otherwise
move freely within the opening 77.
In summary, there has been described herein an alternator and
associated mounting apparatus capable of being coupled directly to
and carried by the end of a rotating axle of a railroad vehicle.
Such coupling allows the use of high-torque alternators having high
energy producing characteristics at both low and high
revolutions-per-minute. Thus, the necessity of having one
rotational energy transmission system to drive an alternator during
cross-country travel, and another for freight yard work, is
precluded. Further, use of "V"-belts and the many problems
attendant therewith is obviated.
By particular embodiment of the present invention has been shown
and described in detail, it is apparent that adaptations and
modifications may occur to those skilled in the art, such
adaptations and modifications being with the spirit and scope of
the present invention, as set forth in the claims.
* * * * *